Scientists said on Friday that human-caused climate change has made the current oppressive heatwave in Western Europe much more likely than it would have been just two decades ago, highlighting the rapidly growing risks to health and livelihoods associated with burning fossil fuels, writes UNN citing The New York Times.
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Emissions of carbon dioxide and other greenhouse gases have been raising temperatures worldwide for more than a century. All this extra heat on the Earth's surface is causing summer weather to produce hotter days and more stifling nights than before.
After examining temperature data over decades, a group of scientists concluded that such intense heat as this week's, over such a large area of Europe, is still rare for June in the current climate, with a probability of less than 1% in any given year.
But in the 2000s, it would have been even rarer, when the Earth's temperature was about 0.6 degrees lower than now. And it would have been "virtually impossible" half a century ago, when the planet's temperature was 1.1 degrees lower, the researchers wrote in their report.
"This event would have been impossible in June without climate change," said the lead author of the report, Theodor Kipping, a climate scientist at Imperial College London. According to Dr. Kipping, the frequency of such heatwaves in the future depends on how much countries can reduce emissions.
The report was prepared by scientists associated with World Weather Attribution, an initiative that analyzes extreme weather events to understand how they have been affected by human-caused global warming.
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This week, a heatwave that broke temperature records from Spain to Germany is the result of a high-pressure system located over Europe, bringing hot air from North Africa. Such heat domes, as they are called, have caused many summer hot spells in Western Europe.
"The weather situation itself is not unusual, but the temperature is — yes," said Friederike Otto, a climate scientist who leads the World Weather Attribution organization. "At least before, without anthropogenic climate change."
In their analysis, the researchers used temperature data to estimate how the likelihood of heatwaves of varying intensity has changed over decades due to global warming. Their results show that a European heatwave, comparable likely to the current one, would have resulted in average daily temperatures in the 2000s being about 2 degrees lower, and in 1976 — 3.5 degrees lower.
The scientists' report has not yet been published in a peer-reviewed journal.
The researchers chose to compare this event with 1976 because that year the United Kingdom experienced another strong summer period. But, according to Dr. Otto, the 1976 heat was not as widespread across Europe as the one observed this week. It was not as humid. And even the record high temperatures reached in the UK in June of that year were exceeded this week, according to preliminary estimates from the country's meteorological service.
The weather conditions that caused this week's heatwave may not have been caused by climate change, but scientists are trying to determine whether climate change is making them more common or persistent in Europe. They are also trying to better understand the complex processes in the atmosphere that generate such conditions.
Better understanding could one day allow forecasters to detect heatwaves much earlier, helping them warn the public weeks in advance, said Dim Coumou, a climate scientist at the VU Amsterdam university in the Netherlands. "The earlier you know, the better adaptation measures you can take," said Dr. Coumou.
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